A combined metabolomic and sensory study on taste development in 'Qiancha 1' summer straight green tea processing

Whether summer-harvested green tea can be processed into acceptable-quality products remains underexplored. This study integrated sensory evaluation, electronic tongue (E-tongue), and metabolomics across fourprocessing stages of 'Qiancha 1' summer straight green tea. Fixation and drying were identified as pivotal stages, E-tongue analysis quantified a 26.51% decrease in astringency intensity and a 29.10% increase in sweetness intensity relative to fresh leaves, which correlated with accumulation of O-/C-glycosylflavones, aromatic amino acids, lysophospholipids, and D-glucurono-6,3-lactone, along with the activation of flavone/flavonol biosynthesis, starch/sucrose, and linoleic acid metabolism. Mantel test identified 29 key flavor-associated metabolites significantly correlated with taste attributes (p < 0.05), including amino acids and derivatives, N-acylpolyamines, nitrogen-containing glycosides, and galloylated flavonol glycosides, which were differentially linked to astringency and sweetness. These findings demonstrate that summer-harvested tea leaves possess considerable metabolic plasticity and provide a mechanistic framework for producing high-quality summer green tea.